Here are some interesting examples of concepts that have a word in foreign languages, but no single word equivalent in English:
Pesamenteiro – Portuguese: one who joins groups of mourners at the home of a dead person, apparently to offer condolences but in reality is just there for the refreshments.
Hanyauku – Rukwangali, Namibia: walking on tiptoes across warm sand.
Tartle – Scottish: to hesitate when you are introducing someone whose name you can’t quite remember.
Prozvonit – Czech and Slovak: to call someone’s mobile from your own to leave your number in their memory without them picking it up.
Pelinti – Buli, Ghana: to move very hot food around inside one’s mouth.
Biritululo – Kiriwani, Papua New Guinea: comparing yams to settle a dispute.
Poronkusema – Finnish: the distance equal to how far a reindeer can travel without a comfort break.
Shvitzer – Yiddish: someone who sweats a lot, especially a nervous seducer.
Gattara – Italian: a woman, often old and lonely, who devotes herself to stray cats.
Baffona – Italian: an attractive moustachioed woman.